Digital audio device

1. A digital audio device, comprising: a memory; an analog input system configured to record analog audio signals to the memory as digital audio data; a digital input configured to download digital audio data, through digital data transmission, to the memory; an analog output system configured to generate analog playback signals decoded from digital audio data stored in the memory; a digital output configured to upload digital audio data, through digital data transmission, from the memory; and a trade connector including a contact configured to mate and cooperate with a complementarily configured and structurally identical contact on a second digital audio device having a structural configuration substantially identical to the digital audio device.

2. The digital audio device of claim 1 , wherein the memory includes semiconductor memory.

3. The digital audio device of claim 1 , wherein the memory includes a nonvolatile memory portion and a volatile buffer memory portion.

4. The digital audio device of claim 1 , wherein the analog input system includes a radio tuner configured to receive the analog audio signals.

5. The digital audio device of claim 1 , wherein the analog input system includes a microphone configured to convert sound energy into the analog audio signals.

6. The digital audio device of claim 1 , wherein the analog input system includes an analog interface configured to receive the analog audio signals.

7. The digital audio device of claim 1 , wherein the analog input system includes an analog-to-digital converter.

8. The digital audio device of claim 1 , wherein the analog input system includes a data compressor.

9. The digital audio device of claim 1 , wherein the analog input system is further configured to selectively transfer the analog audio signals directly to the analog output system.

10. The digital audio device of claim 1 , wherein the analog output system includes a data expander.

11. The digital audio device of claim 1 , wherein the analog output system includes a digital-to-analog converter.

12. The digital audio device of claim 1 , wherein the analog output system includes a signal amplifier.

13. The digital audio device of claim 1 , wherein the analog output system includes a sound transducer configured to convert the generated analog playback signals into sound energy.

14. The digital audio device of claim 1 , wherein the device is configured to adhere to a copyright management scheme.

15. The digital audio device of claim 14 , wherein the digital output is configured to prohibit sharing data associated with a prevention code.

16. The digital audio device of claim 14 , wherein the digital input is configured to convert a restriction code associated with digital audio data to a prevention code when the digital audio data is downloaded, through digital data transmission, from another device.

17. The digital audio device of claim 1 , wherein the trade connector is configured to align the digital audio device in a fixed position relative to the second digital audio device.

18. The digital audio device of claim 17 , wherein the cooperating contacts of the digital audio devices establish a communication path for sharing digital audio data through digital data transmission between the digital audio devices.

19. The digital audio device of claim 1 , further comprising: a radio tuner configured to receive radio signals corresponding to an audio track and a sharing system; wherein the memory is configured to store the audio track as digital audio data; and wherein the sharing system is configured to share the stored digital audio data with another such radio device through digital data transmission between the radio devices.

20. A portable digital audio device, comprising: a memory; an analog input system configured to record analog audio signal to the memory as digital audio data and associate said recorded digital audio data with a restriction code; a digital input system configured to download digital audio data, through digital data transmission, to the memory, and associate said downloaded digital audio data with a prevention code; an analog output system configured to generate analog playback signals decoded from digital audio data stored in the memory; a digital output system configured to upload digital audio data with an associated restriction code from the memory to another device through digital data transmission between the devices; and a trade connector including a contact configured to mate and cooperate with a complementarily configured and structurally identical contact on a second digital audio device having a structural configuration substantially identical to the digital audio device.

21. digital audio device of claim 20 , wherein digital audio data is uploaded to the other device with an associated prevention code to prevent further sharing from the other device.

22. The digital audio device of claim 20 , wherein upon uploading digital audio data associated with a restriction code, the digital output system is configured to convert the restriction code to a prevention code to prevent further uploading from the digital audio device.

23. A portable digital audio device, comprising: an analog interface configured to receive analog audio signals; an analog-to-digital converter configured to convert the analog audio signals into uncompressed digital audio data; a data compressor configured to convert the uncompressed digital audio data into compressed digital audio data; a semiconductor memory configured to store compressed digital audio data; a data expander configured to convert the compressed digital audio data into expanded digital audio data; a digital-to-analog converter configured to convert the expanded digital audio data into an analog playback signal; a digital sharing system configured to share compressed digital audio data with another such portable digital audio device through digital data transmission between the devices, wherein the digital sharing system includes at least a digital input and a digital output; and a trade connector including a contact configured to mate and cooperate with a complementarily configured and structurally identical contact on a second digital audio device having a structural configuration substantially identical to the digital audio device.

24. The digital audio device of claim 23 , wherein the digital output is configured to prohibit sharing digital audio data associated with a prevention code.